Multiple-Choice Questions
1) In Ptolemy's geocentric model, retrograde motion occurs when the planet is closest to us, on the inside portion of the
A) deferent.
B) ellipse.
C) epicycle.
D) equant.
E) ecliptic.
Page Ref: 1.1
2) In Ptolemy's geocentric model, the normal eastward motion of the planets was along
A) a deferent.
B) an epicycle.
C) a retrograde loop.
D) an ellipse.
E) the equant.
Page Ref: 1.1
3) Copernicus' Heliocentric theory explains that
A) Planetary orbits are elliptical in shape.
B) The Sun lies at one focus of an ellipse.
C) Venus retrogrades when she overtakes us at inferior conjunction.
D) All planets lie between the Sun and Earth.
E) Mars will retrograde when it reaches a certain position on its epicycle.
Page Ref: 1.1
4) According to Copernicus, retrograde motion for Venus must occur around
A) interior conjunction, when it passes between us and the Sun.
B) quadrature, when the planet is 90 degrees away from the Sun.
C) greatest elongation, when the planet is farthest from the Sun.
D) superior conjunction, when the planet is on the far side of the Sun.
E) opposition, when the planet lies opposite the Sun in the sky.
Page Ref: 1.1
5) According to Copernicus, the retrograde motion for Mars must occur
A) at inferior conjunction, when Mars laps the earth and passes between us and the Sun.
B) at superior conjunction, when Mars lies on the far side of the Sun.
C) at quadrature, when Mars lies exactly 90 degrees east or west of the Sun.
D) at greatest elongation, when Mars can get up to 47 degrees from the Sun.
E) at opposition, when the earth overtakes Mars and passes between Mars and the Sun.
Page Ref: 1.1
6) A fatal flaw with Ptolemy's model is its inability to predict the observed phases of
A) the Sun during an eclipse.
B) the Moon in its monthly cycle.
C) Mercury and Venus.
D) Mars and Jupiter.
E) Jupiter and Saturn.
Page Ref: 1.2
7) Which of these was NOT a telescopic discovery of Galileo?
A) the rings of Saturn
B) the craters and mare of the Moon
C) sunspots and the rotation of the Sun
D) the four largest moons of Jupiter
E) the phases of Venus
Page Ref: 1.2
8) Which of these observations of Galileo refuted Ptolemy's epicycles?
A) the complete cycle of Venus' phases
B) the rotation of sunspots across the sun's surface
C) the revolution of Jupiter's moons around it
D) the craters on the Moon
E) the visibility of many more stars with the telescope
Page Ref: 1.2
9) Galileo found the rotation period of the Sun was approximately
A) a day.
B) a week.
C) a month.
D) three months.
E) a year.
Page Ref: 1.2
10) Tycho Brahe's contribution to Kelpler's Laws of Planetary Motion were
A) his detailed and accurate observations of the planet's position.
B) his observations of Jupiter's moons.
C) a mathematical explanation of epicycles.
D) a precise lunar calendar.
E) the correct explanation of lunar phases.
Page Ref: 1.3
11) Kepler's first law worked, where Copernicus' original heliocentric model failed, because Kepler described the orbits as
A) elliptical, not circular.
B) much larger than Copernicus had envisioned.
C) around the Sun, not the earth.
D) being on equants instead of epicycles.
E) complex, with epicycles to account for retrograde motions.
Page Ref: 1.3
12) When a planet's orbit takes it closest to the Sun, it's called
A) vernal equinox
B) aphelion
C) perihelion
D) crossing the ecliptic.
E) None of these; a planet's distance from the Sun never changes.
Page Ref: 1.3
14) The force of gravity varies with the
A) product of the two masses.
B) inverse of the distance separating the two bodies.
C) inverse square of the distance separating the two bodies.
D) Both A and B are correct.
E) Both A and C are correct.
Page Ref: 1.4
15) A circular orbit would have an eccentricity of
A) 0.
B) between 0 and 0 .5.
C) between 0.5 and 1.
D) exactly 1.0.
E) infinity.
Page Ref: 1.4
16) How much stronger is the gravitational pull of the Sun on Earth, at 1 AU, than it is on Saturn at 10 AU?
A) 5X
B) 10X
C) 25X
D) 100X
E) 250X
Page Ref: 1.4
17) If the distance between two asteroids is doubled, the gravitational force they exert on each other will
A) also be doubled.
B) be half as great.
C) be one fourth as great.
D) will be 1/16 as great.
E) be four times greater.
Page Ref: 1.4